/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.feilong.lib.io.output;

import java.io.Serializable;
import java.io.Writer;

/**
 * {@link Writer} implementation that outputs to a {@link StringBuilder}.
 * <p>
 * <strong>NOTE:</strong> This implementation, as an alternative to
 * <code>java.io.StringWriter</code>, provides an <i>un-synchronized</i>
 * (i.e. for use in a single thread) implementation for better performance.
 * For safe usage with multiple {@link Thread}s then
 * <code>java.io.StringWriter</code> should be used.
 *
 * @since 2.0
 */
public class StringBuilderWriter extends Writer implements Serializable{

    private static final long   serialVersionUID = -146927496096066153L;

    private final StringBuilder builder;

    /**
     * Constructs a new {@link StringBuilder} instance with default capacity.
     */
    public StringBuilderWriter(){
        this.builder = new StringBuilder();
    }

    /**
     * Constructs a new {@link StringBuilder} instance with the specified capacity.
     *
     * @param capacity
     *            The initial capacity of the underlying {@link StringBuilder}
     */
    public StringBuilderWriter(final int capacity){
        this.builder = new StringBuilder(capacity);
    }

    /**
     * Appends a single character to this Writer.
     *
     * @param value
     *            The character to append
     * @return This writer instance
     */
    @Override
    public Writer append(final char value){
        builder.append(value);
        return this;
    }

    /**
     * Appends a character sequence to this Writer.
     *
     * @param value
     *            The character to append
     * @return This writer instance
     */
    @Override
    public Writer append(final CharSequence value){
        builder.append(value);
        return this;
    }

    /**
     * Appends a portion of a character sequence to the {@link StringBuilder}.
     *
     * @param value
     *            The character to append
     * @param start
     *            The index of the first character
     * @param end
     *            The index of the last character + 1
     * @return This writer instance
     */
    @Override
    public Writer append(final CharSequence value,final int start,final int end){
        builder.append(value, start, end);
        return this;
    }

    /**
     * Closing this writer has no effect.
     */
    @Override
    public void close(){
        // no-op
    }

    /**
     * Flushing this writer has no effect.
     */
    @Override
    public void flush(){
        // no-op
    }

    /**
     * Writes a String to the {@link StringBuilder}.
     *
     * @param value
     *            The value to write
     */
    @Override
    public void write(final String value){
        if (value != null){
            builder.append(value);
        }
    }

    /**
     * Writes a portion of a character array to the {@link StringBuilder}.
     *
     * @param value
     *            The value to write
     * @param offset
     *            The index of the first character
     * @param length
     *            The number of characters to write
     */
    @Override
    public void write(final char[] value,final int offset,final int length){
        if (value != null){
            builder.append(value, offset, length);
        }
    }

    /**
     * Returns the underlying builder.
     *
     * @return The underlying builder
     */
    public StringBuilder getBuilder(){
        return builder;
    }

    /**
     * Returns {@link StringBuilder#toString()}.
     *
     * @return The contents of the String builder.
     */
    @Override
    public String toString(){
        return builder.toString();
    }
}
